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Mathematics 12 Online
OpenStudy (lukecrayonz):

@amistre64 Fourth root of 625i, use the following to complete:

OpenStudy (lukecrayonz):

http://screensnapr.com/e/HaOnvf.png

OpenStudy (anonymous):

5 cos(pi/8)+5 i sin(pi/8)

OpenStudy (lukecrayonz):

..How

OpenStudy (lukecrayonz):

So how did you get theta?

OpenStudy (anonymous):

do you know the position of 625i in the complex plane ?

OpenStudy (lukecrayonz):

Nope.

OpenStudy (lukecrayonz):

|dw:1330663917696:dw|

OpenStudy (anonymous):

it is on the y axis ( imaginary axis ) so the angle is pi/2

OpenStudy (lukecrayonz):

Since its on the imaginary axis?

OpenStudy (anonymous):

yep

OpenStudy (lukecrayonz):

Alright so that makes sense :D

OpenStudy (anonymous):

cool

OpenStudy (lukecrayonz):

so for k, is it just n-1? Or what?

OpenStudy (lukecrayonz):

@amistre64

OpenStudy (amistre64):

for k?

OpenStudy (lukecrayonz):

yes

OpenStudy (amistre64):

4th root is k=0,1,2,3; so 4 solutions using those values each time

OpenStudy (amistre64):

Fourth root of: 0+625i t = pi/2 (90 degrees)

OpenStudy (lukecrayonz):

So if it was 7th root, k=0,1,2,3,4,5,6?

OpenStudy (amistre64):

yes \[\frac{\frac{pi}{2}+2pi(k)}{4}=\frac{\frac{pi+4pi(k)}{2}}{4}=\frac{pi+4pi(k)}{8}\]

OpenStudy (lukecrayonz):

Why is it pi+4pi(k)/2? Where did the dividing by two come into play?

OpenStudy (anonymous):

common denominator

OpenStudy (amistre64):

just simplifying it up by addinging fractions

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